You may be using a high carbon steel rather than alloy steel.
If this is the case, it won't fully harden unless you use a water quench.
If the parts won't harden using a water quench and the part was heated to a bright orange color when it was cooled you may be using a low carbon steel which will never "through harden".
The only thing that can be done with low carbon steel is to carburize it and carburizing will not work if the part is to be used as a spring.
If this is the case, it won't fully harden unless you use a water quench.
If the parts won't harden using a water quench and the part was heated to a bright orange color when it was cooled you may be using a low carbon steel which will never "through harden".
The only thing that can be done with low carbon steel is to carburize it and carburizing will not work if the part is to be used as a spring.